/*
* Copyright (c) 1999, 2007, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package sun.awt;
import java.awt.*;
import java.awt.event.InputEvent;
import java.awt.event.InvocationEvent;
/**
* A stateless class which responds to native mouse moves, Component resizes,
* Component moves, showing and hiding of Components, minimizing and
* maximizing of top level Windows, addition and removal of Components,
* and calls to setCursor().
*/
public abstract class GlobalCursorManager {
class NativeUpdater implements Runnable {
boolean pending = false;
public void run() {
boolean shouldUpdate = false;
synchronized (this) {
if (pending) {
pending = false;
shouldUpdate = true;
}
}
if (shouldUpdate) {
_updateCursor(false);
}
}
public void postIfNotPending(Component heavy, InvocationEvent in) {
boolean shouldPost = false;
synchronized (this) {
if (!pending) {
pending = shouldPost = true;
}
}
if (shouldPost) {
SunToolkit.postEvent(SunToolkit.targetToAppContext(heavy), in);
}
}
}
/**
* Use a singleton NativeUpdater for better performance. We cannot use
* a singleton InvocationEvent because we want each event to have a fresh
* timestamp.
*/
private final NativeUpdater nativeUpdater = new NativeUpdater();
/**
* The last time the cursor was updated, in milliseconds.
*/
private long lastUpdateMillis;
/**
* Locking object for synchronizing access to lastUpdateMillis. The VM
* does not guarantee atomicity of longs.
*/
private final Object lastUpdateLock = new Object();
/**
* Should be called for any activity at the Java level which may affect
* the global cursor, except for Java MOUSE_MOVED events.
*/
public void updateCursorImmediately() {
synchronized (nativeUpdater) {
nativeUpdater.pending = false;
}
_updateCursor(false);
}
/**
* Should be called in response to Java MOUSE_MOVED events. The update
* will be discarded if the InputEvent is outdated.
*
* @param e the InputEvent which triggered the cursor update.
*/
public void updateCursorImmediately(InputEvent e) {
boolean shouldUpdate;
synchronized (lastUpdateLock) {
shouldUpdate = (e.getWhen() >= lastUpdateMillis);
}
if (shouldUpdate) {
_updateCursor(true);
}
}
/**
* Should be called in response to a native mouse enter or native mouse
* button released message. Should not be called during a mouse drag.
*/
public void updateCursorLater(Component heavy) {
nativeUpdater.postIfNotPending(heavy, new InvocationEvent
(Toolkit.getDefaultToolkit(), nativeUpdater));
}
protected GlobalCursorManager() { }
/**
* Set the global cursor to the specified cursor. The component over
* which the Cursor current resides is provided as a convenience. Not
* all platforms may require the Component.
*/
protected abstract void setCursor(Component comp, Cursor cursor,
boolean useCache);
/**
* Returns the global cursor position, in screen coordinates.
*/
protected abstract void getCursorPos(Point p);
protected abstract Component findComponentAt(Container con, int x, int y);
protected abstract Point getLocationOnScreen(Component com);
/**
* Returns the most specific, visible, heavyweight Component
* under the cursor. This method should return null iff the cursor is
* not over any Java Window.
*
* @param useCache If true, the implementation is free to use caching
* mechanisms because the Z-order, visibility, and enabled state of the
* Components has not changed. If false, the implementation should not
* make these assumptions.
*/
protected abstract Component findHeavyweightUnderCursor(boolean useCache);
/**
* Updates the global cursor. We apply a three-step scheme to cursor
* updates:<p>
*
* (1) InputEvent updates which are outdated are discarded by
* <code>updateCursorImmediately(InputEvent)</code>.<p>
*
* (2) If 'useCache' is true, the native code is free to use a cached
* value to determine the most specific, visible, enabled heavyweight
* because this update is occuring in response to a mouse move. If
* 'useCache' is false, the native code must perform a new search given
* the current mouse coordinates.
*
* (3) Once we have determined the most specific, visible, enabled
* heavyweight, we use findComponentAt to find the most specific, visible,
* enabled Component.
*/
private void _updateCursor(boolean useCache) {
synchronized (lastUpdateLock) {
lastUpdateMillis = System.currentTimeMillis();
}
Point queryPos = null, p = null;
Component comp;
try {
comp = findHeavyweightUnderCursor(useCache);
if (comp == null) {
updateCursorOutOfJava();
return;
}
if (comp instanceof Window) {
p = ComponentAccessor.getLocation_NoClientCode(comp);
} else if (comp instanceof Container) {
p = getLocationOnScreen(comp);
}
if (p != null) {
queryPos = new Point();
getCursorPos(queryPos);
Component c = findComponentAt((Container)comp,
queryPos.x - p.x,
queryPos.y - p.y);
// If findComponentAt returns null, then something bad has
// happened. For example, the heavyweight Component may
// have been hidden or disabled by another thread. In that
// case, we'll just use the originial heavyweight.
if (c != null) {
comp = c;
}
}
setCursor(comp, ComponentAccessor.getCursor_NoClientCode(comp), useCache);
} catch (IllegalComponentStateException e) {
// Shouldn't happen, but if it does, abort.
}
}
protected void updateCursorOutOfJava() {
// Cursor is not over a Java Window. Do nothing...usually
// But we need to update it in case of grab on X.
}
}